Biological Psychology

Foundations of Biological Psychology

Historical Overview

  • The foundation of biological psychology is rooted in historical discoveries and understandings of the brain and its functions.

  • A timeline of discoveries is utilized to orient the study of biological psychology.

Early Civilizations and the Brain

  • Egyptian Papyrus (~1700 BCE):

    • The Edwin Smith papyrus is notable for being one of the first recorded uses of the brain.

    • The importance of understanding early contributions to modern biological psychology is emphasized.

    • Egyptian hieroglyphs reflect early knowledge regarding the brain, including recognition of head trauma effects.

  • Recognition of the Cortex:

    • Ancient neuroscientists understood the existence of the cortex (the outer covering of the brain).

    • Awareness of conditions such as seizures and language impairments (aphasias) was present.

    • Knowledge regarding the laterality of movement was established, meaning movement is controlled by the opposite side of the brain.

Philosophical Developments

  • Hippocrates:

    • Considered the brain as the center of thoughts and emotions.

    • There was contention regarding whether the heart was the true seat of consciousness.

    • The debate on the brain's role persisted, with recognition that emotional experiences could be detected through heart rate.

  • Dualism:

    • The question of whether the brain and body are connected or separate arose, introducing the concept of dualism.

    • Rene Descartes:

    • Identified as the father of dualism, proposing that the mind and body are distinct entities.

    • Coined the term "reflex" and described the mind-body interaction as resembling two interactive machines.

    • Influenced by automatons, Descartes believed the mind (or soul) interacted with the body at the pineal gland, thought to be the seat of the soul.

Contributions to Biological Psychology

  • Interaction of Mind and Body:

    • Descartes theorized that actions arose when the soul influenced the pineal gland, subsequently pressuring muscles.

    • Modern science has evolved to understand that consciousness is a product of physiological biological processes, indicating that the mind and body are intertwined rather than completely separate.

Key Discoveries

  • Luigi Galvani:

    • Demonstrated that electrical stimulation could cause muscle contraction, advancing the understanding of nerve function.

    • Johannes Muller:

    • Proposed the concept of specific nerve energies, suggesting that different nerves have distinct functions corresponding to different brain regions.

    • Santiago Ramon y Cajal:

    • Utilized brain staining techniques to depict individual neurons, winning a Nobel Prize for his work.

    • Pioneered the understanding of the nervous system being composed of individual cells (neurons), similar to other body systems.

    • His detailed drawings mirrored what modern microscopy has confirmed about neural networks.

Anatomical Directions:

Neuraxis or CNS: Line drawn through the center of the brain and spinal cord, representing the axis of the nervous system.

PNS: Nerves that branch off CNS

Dorsal: Referring to the top or upper side of an organism (back of us humans) (Supieror)

Ventral: Referring to the beneath or lower side of an organism (Infeiror)

Caudal: Referring to the back or posterior part of an organism (Below of us humans) (Posterior)

Rostral: Referring to the front or anterior part of an organism (Anterior)

Ipsilateral: Referring to structures on the same side of the body (e.g., the right arm and right leg).

Contralateral: Referring to structures on opposite sides of the body (e.g., the right arm and the left leg).

Medial: Middle

Lateral: Referring to structures located towards the sides of the body

Anatomical Cuts:

Sagittal (Perpendicular to the ground)

Horizontal/Transverse (parallel to the ground)

Coronal (Like a deli)

What Is Neuroanatomy

  • Neuroanatomy = structure of the nervous system, especially the brain

  • This unit focuses on macro-level anatomy (whole brain structures)

  • Function at the cellular level comes later

  • Lab focuses on identifying structures on a sheep brain

How We Study the Brain

Lesion Studies

  • Lesion = damage or removal of a brain region to observe lost function

  • Helps establish structure–function relationships

Phineas Gage

  • Damage to frontal lobe

  • Result: poor impulse control, emotional dysregulation, personality change

  • Shows frontal lobe role in inhibition and executive control

Henry Molaison (H.M.)

  • Bilateral medial temporal lobectomy

  • Hippocampi removed

  • Could not form new declarative memories

  • Old memories and procedural learning intact

  • Shows hippocampus is required for memory formation, not storage

Brain Recording & Imaging

  • EEG: excellent temporal resolution (when activity happens), poor spatial

  • MRI / fMRI: excellent spatial resolution (where activity happens), tracks blood flow

  • PET: shows neurotransmitter/metabolic activity

Phrenology (Historical Context)

  • Pseudoscience claiming skull bumps reflect traits

  • Used to justify racism and slavery

  • Incorrect, but introduced idea of regional specificity

  • Modern neuroscience keeps the idea, not the method

Overview of the Nervous System

Central Nervous System (CNS)

  • Brain

  • Spinal cord

Peripheral Nervous System (PNS)

  • Nerves

  • Ganglia

(Class focuses mainly on CNS)

Ventricular System

Ventricles (in order of flow)

  1. Lateral ventricles (I & II) – supply cerebrum

  2. Third ventricle – supplies diencephalon

  3. Cerebral aqueduct – connects 3rd → 4th ventricle

  4. Fourth ventricle – supplies hindbrain and spinal cord

  • Ventricles contain cerebrospinal fluid (CSF)

Cerebrospinal Fluid (CSF)

What CSF Is

  • Clear fluid in ventricles and subarachnoid space

Functions

  • Cushions the brain (shock absorption)

  • Allows brain to float in skull

  • Removes toxins (glymphatic system, especially during sleep)

  • Maintains stable neural environment

Production

  • Produced by choroid plexus in all ventricles

  • Constantly produced and reabsorbed

Clinical Relevance: Hydrocephalus

  • Excess CSF buildup

  • Causes brain compression and atrophy

  • Can result from blocked cerebral aqueduct or poor reabsorption

  • Treated by draining CSF or correcting cause

Cerebral Cortex

General Features

  • Outer layer of brain (“bark”)

  • Composed of gray matter (cell bodies)

  • Inside is white matter (myelinated axons)

Gyri and Sulci

  • Gyri = ridges

  • Sulci = grooves

  • Fissures = deep sulci

  • Purpose: increase surface area → more neurons

Gray vs White Matter

  • Gray matter: processing, develops earlier, declines with age

  • White matter: connections, develops into adulthood, increases efficiency

Major Brain Divisions (Evolutionary Order)

Forebrain

  • Telencephalon: cortex, basal ganglia, limbic system

  • Diencephalon: thalamus, hypothalamus

Midbrain

  • Mesencephalon

Hindbrain

  • Metencephalon: cerebellum, pons

  • Myelencephalon: medulla

Most recently evolved region:

  • Prefrontal cortex (part of telencephalon)

Four Lobes of the Cerebral Cortex

Frontal Lobe

  • Motor cortex (precentral gyrus)

  • Speech production

  • Planning and decision-making

  • Impulse control

  • Executive function

Damage → poor inhibition, personality changes

Parietal Lobe

  • Somatosensory cortex (postcentral gyrus)

  • Touch, pain, temperature

  • Proprioception

  • Spatial awareness

Occipital Lobe

  • Primary visual cortex

  • Processes and integrates visual information

Damage → cortical blindness even with intact eyes

Temporal Lobe

  • Auditory cortex

  • Language comprehension

  • Sound processing and meaning

Listening to music primarily uses the temporal lobe

Limbic System (Subcortical)

Hippocampus

  • Greek for “seahorse”

  • Learning and memory formation

  • Acts as a memory gateway, not storage

  • Essential for consolidation

  • Sleep is critical for hippocampal function

Damage → inability to form new memories (H.M.)

Amygdala

  • Greek for “almond”

  • Fear and anxiety

  • Strengthens emotional memories

  • Site of action for benzodiazepines (e.g., Xanax)

Fear = immediate threat
Anxiety = fear outside of immediate context

Diencephalon

Thalamus (“inner chamber”)

  • Central relay station

  • Gateway for all sensory systems except olfaction

  • Sensory info passes through before reaching cortex

Key nuclei:

  • Lateral geniculate nucleus (LGN) → vision

  • Medial geniculate nucleus (MGN) → hearing

Important exam point:

  • Smell bypasses the thalamus

Hypothalamus (“under thalamus”)

  • Master controller of the endocrine system

  • Controls pituitary gland

  • Regulates the 4 F’s: fight, flight, feeding, mating

  • Produces hormones like oxytocin, vasopressin

  • Regulates growth and sex hormones

Suprachiasmatic nucleus (SCN)

  • Controls circadian rhythm and sleep–wake cycle

  • Receives light information directly from retina

Midbrain (Mesencephalon)

Tectum (“roof”)

  • Superior colliculus: eye movements

  • Inferior colliculus: sound localization

Tegmentum

  • Substantia nigra

    • Dopamine + motor control

    • Degeneration → Parkinson’s disease

  • Ventral tegmental area (VTA)

    • Dopamine + reward

    • Projects to nucleus accumbens

    • Core pathway in addiction, motivation, depression

Hindbrain

Cerebellum (“little brain”)

  • Balance and coordination

  • Procedural/muscle memory

  • Automatic motor skills

  • Involved in fine-tuning movement

Pons

  • Means “bridge”

  • Contains reticular activating system

  • Involved in arousal and wakefulness

Locus coeruleus

  • Regulates alertness and stress

  • Too active → anxiety, poor focus

  • Optimal activity → peak performance

Medulla Oblongata

  • Controls vital functions:

    • Breathing

    • Heart rate

    • Blood pressure

    • Skeletal muscle tone

Damage → incompatible with life

Spinal Cord

Structure

  • Gray matter inside, white matter outside (opposite of brain)

Function

  • Dorsal horn: sensory input enters

  • Ventral horn: motor output exits

  • Capable of reflexes without brain involvement

Example: withdrawing hand from a hot surface before conscious awareness

High-Yield Review Facts

  • Smell is the only sense that bypasses the thalamus

  • Hippocampus = memory formation, not storage

  • Amygdala = fear and anxiety

  • Prefrontal cortex = most recently evolved

  • Cerebellum = automatic movement and procedural memory

  • Medulla = life-sustaining functions